This blog attempts to be a collection of how-to examples in the Microsoft software stack - things that may take forever to find out, especially for the beginner. I see it as my way to return something to the Microsoft community in exchange for what I learned from it.

21 October 2010

My previous post, which caused a bit of a stirrup and got me over 1000 page hits on that one page alone in less than 46 hours, led to the question if I could provide an example of how to use data from Open Source map servers on the web in Bing Maps. This is more useful than Google Maps, since Google’s TOS most likely does not allow accessing their data they way I showed, and an application doing so violates section 3.1 of the Windows Phone 7 Application Certification Requirements, which clearly state that allowed content includes “Copyrighted content that is used with permission”, which I obviously do not have and most likely never will. Unless Google wants to code me a Windows Phone 7 app for them. Hello? Anyone reading along there at Mountain View? ;-)

So anyway, as long as my personal Google Maps for Windows Phone 7 is not going to hit the Marketplace, the Bing Maps MercatorMode can very well be used to show other tile maps, and by popular request I show you how to use data from Mapnik and Osmarender:

The possibility should come as no surprise, since I showed something like this earlier, only then with a plain ole’ MultiScaleImage. All you need to do is, once again, write a class again that descends from Microsoft.Phone.Controls.Maps.TileSource and overrides

Uri GetUri(int x, int y, int zoomLevel)

like I showed in my previous post. And these are even simpler than the Google Maps tilesource. First, Mapnik:

As you see, no rocket science. How to use this classes in XAML is explained in my previous post, and I am not going to repeat that here..

The odd thing is that the Bing Maps logo stays visible, although no Bing Maps data is being used. Notice that the open source maps are displayed in design mode too. So, use any tile server out there that you can legally access and have fun mapping…. although I must admit that is most likely interesting for hardcore GIS fans only, since both servers are considerably slower than Bing – especially OsmaRender, which does some odd things cutting the Netherlands in half, as you see. But still, if not anything else, it shows off the power and versatility of the Bing Maps control pretty well.

For the lazy people, a complete solution – including the Google stuff – can be downloaded here.

19 October 2010

As I write this, we are less than 25 hours away from the moment the first Windows Phone 7 devices are released into the wild – in the Netherlands, that is. The marketplace is filling up nicely already. Some things are pretty obviously missing. And you wonder why, because they would be quite easy to make.

I hereby dare Google to publish a Google Maps application in the Windows Phone 7 Marketplace. Why? Because if they don’t do it, someone else probably will, and probably pretty fast, too. See the screenshot to the left. I assure you – this is no fake. What you see here is the Google Maps satellite layer with the Street layer on top of it, with a 40% opacity, showing a piece of the city center of Amersfoort, Netherlands. It took me about 90 lines of code and 18 lines of XAML.

Setting up a basic Bing Map control is easy as cake. You find the grid “Contentpanel”, and you plonk a Map in it, preferably using Blend:

You can change “Road” into “Aerial” and then you have Bing Satellite imagery. What’s less known is that you can actually attach your own tile layers to it. A tile is an image of 256x256 defined by it’s X and Y position in the grid forming the map of the world on a specific zoom level. All you have to to is write a little class that descends from Microsoft.Phone.Controls.Maps.TileSource in which you only have to override the following method:

Uri GetUri(int x, int y, int zoomLevel)

in which you tell which x/y/zoomlevel combination translates to which URI. For Google Maps, this turns out to be pretty easy. All information needed for can be found in the Deep Earth source code – a wee bit adapted for for the Bing Map Control. First, I made an enum that defines all the layers that Google provides

The Bing Maps control makes you able to zoom and pan trough all this. Okay, Google Maps does a little more than this, but this shows pretty well how darn easy it is to make a good looking, pretty fully functional mapping application showing totally different imagery.

Conclusion: using the Bing Maps Control for showing raster maps is so bloody easy that I almost start to wonder if it’s still justified to feel proud ‘being a GIS guy’. Almost ;-)

17 October 2010

This article does technically not belong to this blog, for it does not contain any code samples – in fact it does not handle code at all. But since the launch of Windows Phone 7 is a very special occasion and the devices will hit my country (the Netherlands) very soon I thought it important enough to break rank for once.

For all kinds of reasons – mostly legal, I’ve been told - about 17 countries are included in the Marketplace for Windows Phone 7. This by no means that you cannot be part of the fun of the Windows Phone 7 launch if you are not inside the USA or any of the other countries – like me. All you have to do to view the Windows Phone 7 apps that are currently in the Marketplace is follow the simple procedure below:

Browse to www.msn.com. This will redirect you to your local msn (in my case, nl.msn.com) but will also provide you with a popup that lets you choose between your local msn.com and the USA msn.com. Choose the USA version

If you are signed in with your live ID, sign out

Create a new live ID that has its location in the USA. You need to provide an USA state and ZIP code that actually exist and match. Which can be easily obtained via this site. Simply click somewhere on the map, choose one of the cities it suggests, and presto – one existing zip code and state combination

Start up the Zune software

Login with your freshly created live ID

Provide your birth date

Click Marketplace

Click Apps

And there you are

Update according to Rob Houweling this procedure will only work if the OS language is set to English. See comment. Thanks Rob!

Update 2 this works on a Windows Phone 7 as well. Tom Verhoeff has a blog post which explains (in Dutch) how you can setup a phone to use a specific Live Id that has it's location in the UK and a billing adress in the UK that will allow you to buy apps using an ordinary Dutch credit card.

Bear in mind that your local Microsoft office does not support this procedure, so when you have problems you are basically on your own. But that is what you have your local Microsoft community for - they can probably help you out, and if not, there are plenty of Microsoft employees who will help you out sub rosa – if you just ask the right person kindly enough. After all, we’re all in the same boat ;-)

06 October 2010

The very first Silverlight application I had to make professionally (i.e. not as a hobby/research project at home) required the possibility to open a file from (local) disk. Of course I wanted to use Laurent Bugnion’s MVVMLight and the strict separation between logic that I talked and blogged about so much – ‘practice what thou preach’, eh?

This proved to be an interesting challenge. The most logical way forward seemed to be: make a button, attach a command to it via the usual EventToCommand route and then use OpenFileDialog from the model – which landed me a “Dialogs must be user-initiated” error. Googling Binging around I found out that Dennis Vroegop had run into this thingy quite recently as well.

Things looked ugly. Getting around it took me some code in the code behind. This kept nagging me, and only recently I found a better way to deal with this. Apart from the EventToCommand binding MVVMLight contains another gem, called the Messenger. This is an implementation of the Mediator pattern that - as far as I understand – is designed to broadcast property changes between different models in the application. But this mechanism can also be used as an alternative way to shuttle data from the GUI to the model in a designer-friendly – Blendable -way. The way to go for this particular problem is like this:

Define a message that holds the data from an OpenFileDialog

Make a behavior that can attach to a button that launches an OpenFileDialog on click, and then sends a message on the Messenger

Register a listener on the Messenger in the model for that particular message

True to my blog’s title, I will demonstrate this principle with an example. First, a message containing the result of an OpenFileDialog:

Notice that the message also contains a property Identifier, acting like an optional additional message identifier. This is necessary, since the MVVMLight messenger seems to identify messages by type. Therefore, every method listening to a FilesOpenedMessage gets a message, and the various models would have no way to know if it was actually for them to act on it. Identifier makes coupling a particular listener to a particular sender possible. I’m sure there are other ways to get this done, I simply chose the simplest.

The “Content” property of the message always contains the payload, i.e. whatever you had to pass to the message constructor – in this case, an IEnumerable<FileInfo>. In XAML you then bind the whole thing together like this, like any ordinary behavior:

The Listbox is used to display the names of the selected files. I did leave this out, there’s enough code in this sample already. For those who want to have the full picture: a complete solution demonstrating the behavior can be found here.

Notice there’s an important difference using this technique in stead of the EventToCommand: when the user presses the button, the model cannot control the actual display of the OpenFileDialog: the click is handled by the behavior, not the model itself (via EventToCommand) and the OpenFileDialog is always displayed once the button is clicked. Therefore, the model should control if the user can press the button at all, which is done by binding the IsEnabled property to a property of the model (CanOpen – sorry, lame pun). Which is good UX practice anyway – controls that cannot be used should be disabled in stead of giving a ‘sorry, you can’t do that’ message whenever possible, but in this case it’s simply necessary.

I only showed how to do open a file from disk, but a pattern like this can be used to save files to disk as well, or do other things that might seem to require coding in the code behind file. That is no sin in itself – nobody from the MVVM police will show up at your doorstep and take your family away if you need to do that. At least that is what Laurent himself promised at his MIX10 talk ;-). But by coding a behavior, you enable designers to add fairly easily relatively complex actions using Blend without having to dive too deep into XAML. Using behaviors like this FileOpenBehavior makes it even easier to add interactivity than the EventToCommand (which was closed off anyway during security restrictions).

It can’t hurt to be nice to your designers – after all, they make the pretty stuff up front that makes your application sell ;-)

Oh, and one final thing: in all my previous posts I was talking about ‘behaviour’ in stead of ‘behavior’. I hope you all will excuse me for being educated in the Queen’s English, even tough I am just Dutch. ;-).

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If you spot things that are incorrect, or if you don't understand what I mean, please drop a comment on the offending article and I will help you ASAP. You can e-mail me at joostvanschaik at outlook dot com or contact me via twitter.

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Although I take great care in providing quality samples, all postings, articles and/or files on this site are provided "AS IS" with no warranties, and confer no rights. The views expressed on this blog are strictly my own and do not necessarily reflect the views of my employer, or anyone else on the planet for that matter.

I usually make original content, sometimes building upon other people's work. Sometimes I explain things that can be found elsewhere because I felt what I read was not clear enough for my limited mind so I explain it the way it finally clicked with me. In all cases I take great pains to be sure to link to people or articles who deserve the credit. If you think I have shortchanged you on the credits please let me know.

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